This invention relates to heat-sealable polybutene-1 polymer blends.
It is known that polybutene-1, especially in the isotactic structure, possesses a number of advantageous properties as compared to other polyolefins. In many applications, these advantages are overshadowed by the difficulty of establishing durable and firm weld bonds of shaped articles, such as pipes or film, of polybutene-1; in particular, the resistance to further rupture or tearing is insufficient for many purposes of application.
Therefore, numerous attempts have been made to improve the weld strength of such films. According to German Unexamined Published Application No. 2,012,913 and U.S. Pat. No. 3,634,551, the polybutene-1 is admixed with about 1-5% weight of a low density polyethylene. This polyethylene is produced in accordance with the high-pressure method and has a density of 0.910 to 0.925; high density polyethylenes are said to be unsatisfactory because they produce erratic results.
In spite of prior art failures, it would be desirable to employ high-density polyolefins obtained according to the low-pressure process as additives to polybutene-1, since such a mixture would be composed exclusively of low-pressure polyolefins, thereby affording a better compatibility of the individual blend components and accordingly a reduction in the potential adverse effects of the additive on the valuable physical properties of polybutene-1.